Aerosol bottles formed from plastic materials have been proposed as a new alternative to metal bottles. Plastic bottles would give manufacturers increased freedom in developing unique canister shapes, developing clear packages, giving an improved sustainability profile vs. metal and lowering manufacturing costs. Poly(ethylene terephthalate) (PET) has been suggested as a useful plastic material for aerosol bottles, since it is clear and can be recycled. However, limonene and other perfume raw materials (prms), as well as hydrocarbon propellants and other formula ingredients (or even just water in some cases, with different results depending on the pH of the water), can diffuse into PET, especially in high pressure environments, and lower its crazing initiation stress. As a result of that, these chemicals can cause crazing of PET in the neck and shoulder regions of an aerosol bottle where the tensile stresses, due to the presence of the pressurized propellant and small radii of curvature, exceed the crazing initiation stress. Crazing is more predominant in these regions, since they tend to be more amorphous than in the more highly crystalline and stretched regions of the bottle, where the PET molecules are more aligned and diffusivity of the ingredients is lower. This crazing of PET can progress into cracking (particularly at higher strains and when exposed to substances, such as bleach, which can cause hydrolytic cracking) and cause integrity problems in aerosol bottles and is potentially dangerous: a weakened plastic aerosol could lead to a compromised bottle that could release the gas/product contained within uncontrollably and thus be unacceptable from a product safety viewpoint.
Therefore, a need still exists for an aerosol bottle that can be formed from a recyclable plastic material that has better resistance to crazing than PET.